The invention relates to a machine for packaging fragile cylindrical products, particularly cigarettes, comprising:
a unit for forming ordered groups of cigarettes, particularly according to the arrangement which they are intended to have in the packet, and for transporting the ordered groups of cigarettes;
a station for transferring the ordered groups, one at a time and successively, to a unit for combination with a first wrapping slip, to which transfer station the ordered groups of cigarettes are supplied successively from the forming and transport unit;
means of transferring the ordered groups of cigarettes, synchronized with the unit for forming and transporting the ordered groups;
means of checking the correct formation of the ordered groups of cigarettes, these means being provided along the transport path of the ordered groups before the transfer station;
means of ejecting incorrectly formed groups of cigarettes, these means being disposed along the transport path of the ordered groups of cigarettes, in a position intermediate between the checking means and the transfer station, and being controlled by the checking means so that their operation is synchronized with the forming and transport unit when an incorrectly formed group of cigarettes is detected.
To ensure high output, in other words a large number of packets of cigarettes per unit of time, packaging machines of the said type have to be driven at very high operating speeds. This entails considerable difficulties of synchronization and requires arrangements capable of ensuring that the conditions for synchronization are maintained in time and within the required precision limits. The high operating speed of the individual units which operate in a reciprocating way also entails dynamic problems, since inertial masses have to be accelerated and decelerated with high frequency and precision, and therefore attempts are made to keep these masses advantageously limited. The achievement of these objects frequently obliges manufacturers to adopt extremely complex and expensive solutions, which make the machines significantly sensitive to problems of malfunctioning and which also complicate maintenance and servicing operations.
The object of the invention is therefore to provide a packaging machine of the type described initially, with which, owing to simple and relatively inexpensive arrangements, it is possible to obtain a high operating speed and more compact construction with a lower inertial mass, while ensuring the necessary synchronization for long periods and without excessively limiting the possibility of executing maintenance and servicing operations.
The invention resolves this problem with a packaging machine of the type described initially in which the means of transfer from the forming and transport unit to the unit for combination with the first wrapping slip and the means of ejecting incorrectly formed groups of cigarettes are made substantially identical to each other and are operated in phase with each other by a single common operating mechanism in the transfer and ejection strokes and the return strokes, the ejection means being additionally movable transversely with respect to the ejection stroke by associated means of diverting the ejection stroke from a trajectory in which the ejection means interact with the group of cigarettes to be ejected to a trajectory in which they do not interfere with the group of cigarettes, these diverting means being controlled by the cigarette group checking means in synchronization with the advance of the tubular housings.
The ejection means and the transfer means are made in such a way that they move in identical strokes for transferring and ejecting groups of cigarettes, the strokes being synchronized in phase, rectilinear and parallel to each other, in a predetermined plane, while the ejection means are additionally movable in the direction of a component of motion transverse to the ejection stroke by means of an operating mechanism which is controlled by the checking means and which diverts the ejection stroke to a plane which is moved laterally, and particularly vertically, out of alignment with the group of cigarettes.
When the means of forming the groups of cigarettes consist of what is known as a tray conveyor, in other words a continuous conveyor belt provided with a plurality of tubular housings for the ordered groups of cigarettes, these housings being made to advance in steps and being open at their ends which are laterally orientated with respect to the direction of transport, the transfer stroke and ejection stroke are executed in the direction of the axes of the housings perpendicular to the said ends, the transfer means and the ejection means being disposed coaxially with the open ends of the housings at points which are spaced apart in the direction of transport along the tray conveyor, and at which the housings are in the stopping phases between the advance steps.
To provide a higher operating speed of the machine by limiting the stopping phase to the time required for the execution of the ejection and transfer stroke only, the ejection and transfer means are provided with a pushing beam whose shape is complementary to that of the transverse section of the tubular housings and which is carried on and projects from a thin supporting stem orientated transversely and preferably perpendicular to the upper free surface of the housings and to the transfer or ejection stroke, while the housings are provided with a slit for the passage of the said stem, the slit being orientated in the direction of the transfer or ejection stroke and extending from one end to the opposite end of each housing. The transfer and ejection stroke is such that at the end point of the ejection and transfer stroke both the supporting stem and the pushing beam are disengaged from the housing. The transfer means are also made movable in the direction of an additional component of motion transverse with respect to the transfer stroke, by diverting means separate from those of the ejection means, in such a way that the transfer means execute the return stroke in a trajectory in which they do not interfere with the housings.
In a preferred embodiment, the transfer means and the ejection means comprise a push bar which is orientated in the direction of the transfer and ejection stroke and which at its end facing the housings carries the stem and pushing beam, this push bar being hinged to an articulated quadrilateral for providing the transfer and ejection strokes and the corresponding return strokes along a rectilinear path, while the said push bar, together with the said articulated quadrilateral, also forms part of an articulated parallelogram, the articulated quadrilaterals of the transfer means and of the ejection means and the associated articulated parallelograms being identical to each other and being provided with transmission arms operated in synchronization by a common operating mechanism, while each articulated parallelogram has a rocker arm parallel to the transmission arm of the articulated quadrilateral, at least the rocker arm of the ejection means being pivoted on an axle which is movable transversely with respect to the ejection stroke by means of its own operating mechanism. The rocker arm of the articulated parallelogram of the transfer means is also pivoted on an axle which is movable substantially transversely with respect to the transfer stroke and which is operated by a separate operating mechanism.
The advantages of the present invention will be clear from the above description. The ejection means and the transfer means are made so that they are substantially identical to each other and move along identical paths in full synchronization of phase with each other, in the conditions of operation of the ejection means. To obtain the necessary synchronization with the stopping phases of the ordered groups along the transport path at the transfer station, it is therefore sufficient to synchronize only three operating mechanisms, namely the common operating mechanism of the transfer and ejection stroke and the corresponding operating mechanisms for the transverse movement. In particular, since the transfer means are operated continuously, while the ejection means are activated only irregularly, the motion for the transverse movement of the return stroke of the transfer means with respect to the transfer stroke may be obtained from a single motor which is also common to the operating mechanism of the transfer stroke, by using suitable synchronized transmission means. In addition to the reduction of inertial mass due to this particular embodiment, the mass is further limited by the construction of the transfer and ejection means in the form of articulated quadrilaterals associated with articulated parallelograms, thus providing considerable simplicity of construction and reliability of operation.